Puro D G, Mano T
Department of Ophthalmology, University of Michigan School of Medicine, Ann Arbor 48105.
J Neurosci. 1991 Jun;11(6):1873-80. doi: 10.1523/JNEUROSCI.11-06-01873.1991.
The objective of this study was to begin to examine the cellular and biophysical effects on human retinal glial cells of basic fibroblast growth factor (bFGF), which is endogenous to the retina and likely to play a role in retinal pathobiology. Experiments were performed on cultured glial cells derived from the adult postmortem retina. A proliferative response to bFGF established a sensitivity of the retinal glia to this growth factor. The possibility that bFGF alters calcium currents was assessed using the whole-cell recording configuration of the patch-clamp technique to analyze inward currents carried by barium. Two types of voltage-gated calcium channels could be expressed by the glial cells. One, similar to the T-type current described in various kinds of cells, had a low threshold of activation, a transient response, and an insensitivity to the dihydropyridine nifedipine. The other type of inward current, which closely resembles the L-type calcium current found in other cells, had a high threshold, had a long-lasting response, and was inhibited by nifedipine. When continuous whole-cell recordings were made from retinal glial cells, the L-type calcium current increased significantly within 20 min after exposure of the cells to bFGF. The physiological significance of this modulatory effect remains uncertain, though the observation that nifedipine inhibits both the L-type calcium current and the bFGF-induced proliferation is consistent with the hypothesis that dihydropyridine-sensitive channels may play a role in modulating the mitogenic response of retinal glial cells to this growth factor.
本研究的目的是开始研究碱性成纤维细胞生长因子（bFGF）对人视网膜神经胶质细胞的细胞和生物物理效应，该因子是视网膜内源性的，可能在视网膜病理生物学中发挥作用。实验在源自成人死后视网膜的培养神经胶质细胞上进行。对bFGF的增殖反应确立了视网膜神经胶质细胞对这种生长因子的敏感性。使用膜片钳技术的全细胞记录配置来分析钡携带的内向电流，评估bFGF改变钙电流的可能性。神经胶质细胞可表达两种类型的电压门控钙通道。一种类似于在各种细胞中描述的T型电流，具有低激活阈值、瞬态反应且对二氢吡啶硝苯地平不敏感。另一种内向电流与在其他细胞中发现的L型钙电流非常相似，具有高阈值、持久反应且被硝苯地平抑制。当从视网膜神经胶质细胞进行连续全细胞记录时，在细胞暴露于bFGF后20分钟内，L型钙电流显著增加。尽管硝苯地平抑制L型钙电流和bFGF诱导的增殖这一观察结果与二氢吡啶敏感通道可能在调节视网膜神经胶质细胞对该生长因子的有丝分裂反应中起作用的假设一致，但这种调节作用的生理意义仍不确定。
